Switch means for indicating time intervals



Sept. 26, 1950 R. TELFORD 2,523,602

SWITCH MEANS FOR INDICATING TIME INTERVALS Filed July 22, 1946 2 Sheets-Sheet 2 11 1 1s 1s a 17 ,/f 1o 14 16 i //Vl EJV 70 Q, fa/MAD TE 4 FORD Patented Sept. 26, 1950 OFFICE SWITCH MEANS FOR INDICATING TIME INTERVALS Ronald Telford, Newport, Isle of Wight Application July 22, 1946, Serial No. 685,343 In Great Britain July 23, 1945 Claims.

This invention relates to a device for indicating by electrical means the lapse of predetermined time intervals and has for its object the provision of improved and simple means which can be rendered operative at any instant and will then indicate the expiration of a period of time of the selected or predetermined length commencing from the said instant.

According to the invention, a device for ind-icating by electrical means the lapse of predetermined time intervals comprises a driven element rotated at a constant speed, a pivoted switch lever carrying one electrical contact, disposed adjacent to the said driven element and biased toward another electrical contact serving as a stop for said lever, a pivot carried on the switch lever, a rotatable element eccentrically mounted on the said pivot so that in the normal position of the switch lever it is spaced slightly from the driven element with its maximum eccentricity disposed towards the latter, and latch means normally holding the switch lever away from the contact stop and manually operable to release the pivoted lever at any selected instant to allow the eccen-.

trically mounted element thereon to move into contact with and be driven by the driving element, the consequent rotation of the eccentrically.

mounted elementabout .its pivot on the lever gradually reducing the gap between the latter and its stop so that the gap is closed at the expiration of a predetermined time interval, thereby completing an electrical warning circuit.

The contact stop referred to is preferably adjustable in relation to the pivoted switch lever so that the duration of the predetermined time interval may be varied as required and a plurality of pivoted switch levers and eccentrically mounted elements may co-operate with a single driven element, the contact stops being either adjustable in common, so that all the switch levers will be operated into engagement with thei contact stops in the same period of time (though measured from different starting points if required) or individually adjustable, so that each switch lever will be operated into engagement with its contact stop in a different period of time (again from different starting points if.

required).

The engagement of the pivoted switch lever with its contact stop is utilized to operate a visual signal or an audible warning, or both, but such engagement may additionally be utilised to effect any desired operation, either directly or indirectly, any desired operation which can be initiated or controlled by the completion of an electric circuit.

In order that the invention may be clearly understood and readily carried into effect, reference will now be made to the accompanying drawings which illustrate one embodiment of iii the invention by way of example. drawings:

Figure 1 is a plan view of the apparatus with a cover removed to expose the mechanism.

Figure 2 is a section taken on the line II-II of Figure 1 but including the cover, the parts of the mechanism being shown in a non-operating position, and

Figure 3 is a view similar to Figure 2, but showing the position of the parts after they have been operated.

The example chosen comprises a plurality of pivoted switch levers and eccentrically mounted elements but, as they are identical in construction and function, only one will be described in detail.

Referring to the drawings, a rolleri covered with material 2 having a high co-eflicient of friction is rotatably mounted between the end walls of a casing 3 near the rear wall 4 thereof and driven at a constant speed by suitable means, for example, a spring-driven clockwork, a synchronous A. C. electric motor or other suitable source of power transmitted at constant speed, this power source being indicated diagrammatically at 5. A pivot spindle 6 is arranged to extend within the casing 3 near the front wall 1 thereof, and parallel with and at a higher level than the axis of the roler l. Freely pivoted In the on the spindle B is a two-armed switch lever 8 having its shorter arm 9 directed towards the front casing wall I and formed with an abutment IIJ engageable with the inner end I I of latch means in the form of a holding key that is pivoted on a spindle ['2 adjacent to the front wall I, and extends at its outer end l3 through a slot I4 in this wall I. The longer arm l5 of the switch lever 8 extends over and beyond the roller l to terminate in an electric contact l6 and carries at a point substantially vertically above the axis of the roller l a lateral pivot l1 onwhich is freely rotatable a circular disc l8 engaged with the pivot IT by means of an eccentric aperture near its edge. The disc I8 is of a diameter approximately twice that of the roller I. Mounted to swing about the pivot spindle 6 is an arm or frame l9 carrying another electric contact 20 constituting a stop at the same radial distance from the spindle 6 as the contact I6 on the switch lever B and disposed beneath the latter. The position of the contact stop 20 is fixed by means of a clamping nut carried on the arm or frame IS the bolt 22 extending through an arcuate slot 23 in the one end wall 24 of the casing 3, this wall 24 carrying alongside of the arcuate slot suitable graduation marks indicating time intervals.

In the normal inoperative position of the parts as shown by Figure 2 the abutment ill on the switch lever B is engaged by the inner end I l of 21 engaged with a bolt 22 3 the latching key and thereby held depressed so that the longer lever arm i5 is raised away from the contact stop 2- 3 by an amount permitting the disc 28 to hang freely above the roller i with the lower part of its periphery spaced slightly from the latter.

When the outer end 13 of the latching key is depressed to release the switch leve B the longer arm 15 thereof with the disc 58 drops until the latter rests on the roller driven by the roller 3 about its pivot ll on the switch lever 8 and, due to its eccentric mounting, the said pivot i? is gradually lowered until the contact 86 on the leve 15 meets the contact stop 22. The time taken to bring the contacts 56 and 26 together depends on the degree of initial separation thereof.

The contacts I8 and are connected into an electric circuit which includes a signal lamp 25 associated with the appropriate latching key on the front of the casing 3 and which may include also an audible warning device, such as an electric bell or buzzer. Raising of the outer end I3 of the latching key will re-set the pivoted switch lever B in its raised position and interrupt the circuit to the signal devices.

One application of the apparatus described is as an indicator for use by the proprietor of a number of articles (such as boats, cars, etc.) which are to be hired out for relatively short periods of time, of the order of half-an-hour, to members of the public. A plurality of ivoted levers 8 is provided with'the key for each indi cated by a number corresponding to the cation number of an article. The proprietor, therefore, merely depresses the correspondingly numbered latching key as an article is hired and is given warning automatically as-the period of time for which that article was hired'cx'p ires.

Another application is asan' indicatorfor use in kitchens, laboratories and other places where a process requiring a certain fixed period of time for its com'pletion is to be repeated continually. The stops o contacts '20 in such'a case would preferablv be individually adjustable.

It will be understood that the size or shape of the (or each) eccentrically mounted disc E8 on the (or each) pivoted lever B may be varied so as to provide contours of diiferentlengths providing for any desired time lapses before the released switch levers are arrested by their respective contact stops,

I claim:

1. A device for indicating time intervals elec trically, comprisinga pair of pivoted contact members both angularly displaceable in substantially the same plane so that thei contacts move towards or away from each other, adjustable means maintaining oneof said members in a pre-' selected angular position, an eccentricconnected to the other of said members and a drive member rotatable by a source of power, said drive member being drivingly engageable with. said eccentric so as to move saidsecondmember into contact with said first member.

2. A device for indicating time intervals elec trically, comprising, a pair of pivoted contact The disc i3 is then members both angular-1y displaceable in substantially the same plane so that their contacts move towards or away from each other, adjustable means maintaining one of said members in a preselected angular position, a driven element the other member has a second arm and the other.

means is a releasable holding key engaging said second arm and retaining the eccentric free of the driven element.

4. A device forindicating time intervals electrically, comprising, 2, pair of pivoted contact members mounted on a common pivot'and both angularly displaceable in substantially the same plane so that their contacts move towards 'or away from each other, adjustable means maintaining one of said members in a preselected angular position, a driven element rotatable at constant speed and disposed exteriorly of the pivoted members and between the common'pivot and the path of the contacts, and an eccentric carried by the othe ofsaidmembers and 'engageable with said driven element and rotating the other member toward the'nrst'member to cause engagement of the contact members.

5. A device'for indicatingitime intervals electrically, comprising, a pair of contact members mounted on a co'mmon'pivot 'for angular displacement in substantially the'same plane so that their contacts move toward orlaway from each other, one of said members'bein'g atwo-armed lever, an

eccentric carried by the largerarm of said member and biased toward the other contact member, adjustable means maintaining the other contact member inia preselected angular position, a driven roller rotatable at constant speed and dis posed exteriorly of the two members and engageable by-the eccentric toidrive same, a holding key 'engageable with the shorter arm to retain the eccentric free of the roller whereby upon operation of the holding key the two-arm member is released for movement toward the other member by the coaction of the eccentric and the roller so as to cause the contacts to engage.

RONALD TELFORD.

REFERENCES CITED UNITED STATES PATENTS Name Date Steiner Feb. 29, 1916 Huebner Apr. 17, 1917 Number Rhodes -Mar. 2, 1942 

